dccp: Add check for truncated ICMPv6 DCCP error packets

This patch adds a minimum-length check for ICMPv6 packets, as per the previous
patch for ICMPv4 payloads.
Signed-off-by: NWei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>

net/dccp/ipv6.c

@@ -96,6 +96,12 @@ static void dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	__u64 seq;
 	struct net *net = dev_net(skb->dev);
 
+	if (skb->len < offset + sizeof(*dh) ||
+	    skb->len < offset + __dccp_basic_hdr_len(dh)) {
+		ICMP6_INC_STATS_BH(__in6_dev_get(skb->dev), ICMP6_MIB_INERRORS);
+		return;
+	}
+
 	sk = inet6_lookup(net, &dccp_hashinfo,
 			&hdr->daddr, dh->dccph_dport,
 			&hdr->saddr, dh->dccph_sport, inet6_iif(skb));